Objective: To determine whether the decline in CA 125 level after surgery can predict the extent of residual disease.
Methods: In a prospective, nonrandomized clinical trial, 27 women with advanced ovarian cancer (stage III or IV) underwent primary or secondary cytoreductive surgery. CA 125 levels were measured before surgery and 3-14 days postoperatively. The mean postoperative decline was compared by size of residual disease.
Results: In women with all visible cancer resected, the mean (+/- standard error of the mean) decline in CA 125 was 91 +/- 4% (1032 +/- 473 U/mL preoperatively to 90 +/- 31 U/mL postoperatively). With less than 2.0 cm residual, there was an 85 +/- 2% decline in CA 125 after surgery (3061 +/- 835 U/mL preoperatively to 456 +/- 146 U/mL postoperatively). In patients with residual disease larger than 2.0 cm, the levels dropped 36 +/- 10% (2958 +/- 1587 to 1904 +/- 708 U/mL). If CA 125 declined less than 60% from the preoperative level, the sensitivity, specificity, and positive and negative predictive values for residual disease larger than 2.0 cm were all 100%.
Conclusion: By using the ratio of CA 125 levels before and after cytoreductive surgery, one can predict the likelihood that the patient was left with less than 2.0 cm residual disease.